1. Field of the Invention
The present invention relates to thermoplastic polyblends based on fluoropolymers and aromatic polyesters, and comprising a compatibilizing agent therefor.
This invention especially relates to compatibilizing agents comprising copolymers of ethylene, glycidyl acrylate and an acrylate, for thermoplastic resins based on fluoropolymers, notably polyvinylidene fluoride, and on aromatic polyesters, notably a polyterephthalate.
2. Description of the Prior Art
It is known to this art that fluoropolymers have very good mechanical properties, excellent thermal and weathering behavior and markedly good chemical inertness and resistance.
However, because of their high density, the complexity of the applications thereof and their high cost, it has been proposed to combine them with other polymers, in particular, to polyblend same with aromatic polyesters, whose good mechanical, electrical, chemical and thermal properties are also known to this art.
Such blends, comprising fluoropolymers and aromatic polymers, have mechanical properties which provide little satisfaction. In particular, their low elongation at break and their mediocre impact strength are a result of poor adhesion between the fluoropolymer phase and the aromatic polyester phase.
To improve the mechanical properties of such blends, a compatibilizing agent must be added thereto to promote cohesion between the phases.
FR-2,389,658 describes thermoplastic blends based on fluoropolymers and aromatic polyesters which contain a compatibilizing agent. The compatibilizing agent is a block copolymer of an intermediate polymer block of a conjugated diene which is endblocked with a polymer block of a monoalkenylarene. The presence of the compatibilizing agent permits an alloy to be obtained which has a more homogeneous appearance but which, disadvantageously, does not exhibit any improvement in the elongation at break. Moreover, it is necessary to incorporate at least 30% of compatibilizing agent into the blend in order to provide an increase in the impact strength.